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Author Topic: No 12v power to ignition.  (Read 1851 times)

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Offline 75 super sport

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No 12v power to ignition.
« on: February 28, 2012, 10:21:45 AM »
I have no 12v power going to anything. No lights work, or horn. What is the correct way to test for 12v going to the ignition? With a multi meter I put the positive on the red wire coming to ignition, then the negative grounded to the frame. Shows no voltage. I have 12v going to the rectifier( I believe that is what it is). New to the cb750 and trying to get the bike running that i just purchased. Any tips to atleast get power to the ignition? Thanks in advance for the help!
« Last Edit: February 28, 2012, 10:27:00 AM by 75 super sport »
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Offline ChuckG750f1

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Re: No 12v power to ignition.
« Reply #1 on: February 28, 2012, 10:40:04 AM »
The red lead to the ignition is fused (15 A).  Is the fuse good?  Do you have the correct wiring diagram for your bike.  I have a '76 f1 (same wiring).
« Last Edit: February 28, 2012, 10:43:24 AM by ChuckG750f1 »
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Offline Kurt V

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Re: No 12v power to ignition.
« Reply #2 on: February 28, 2012, 10:43:16 AM »
Kickstand kill switch stuck?
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Offline 75 super sport

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Re: No 12v power to ignition.
« Reply #3 on: February 28, 2012, 10:47:49 AM »
I am not familiar with kickstand kill switch? Where is this located?
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Offline 75 super sport

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Re: No 12v power to ignition.
« Reply #4 on: February 28, 2012, 10:57:57 AM »
Ok found that fuse, it was bad. Put one in, lights turned on and had power to ignition. There was a solenoid looking thing with three prongs, 1 black, brown, and green wire it says flasher on the side of it? Well that started clicking like a blinker would, then it stopped and my lights stopped with it. The fuse is still fine, what is the flasher? Thanks again for the help!
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Offline ChuckG750f1

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Re: No 12v power to ignition.
« Reply #5 on: February 28, 2012, 11:25:39 AM »
OK, that is the turn signal relay.  It should not be active if the turn signal switch is in the middle position.  If the switch was in the middle position when it was clicking then you may have broken/shorted wires in the left side control (high/lo beam, horn and directionals).  I can e-mail you the wiring diagram if you want.  -Chuck
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1995 HD Softail Custom

Offline 75 super sport

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Re: No 12v power to ignition.
« Reply #6 on: February 28, 2012, 11:34:18 AM »
please do, i think that might help. there were two wires connected to the relay, then a green wire which i assumed was ground which was hanging by the third terminal and i hooked that up. was that not supposed to be plugged in? thanks again
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Offline ChuckG750f1

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Re: No 12v power to ignition.
« Reply #7 on: February 28, 2012, 11:44:39 AM »
Green wire should not be connected.  Give me your e-mail address.  -Chuck
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1995 HD Softail Custom

Offline 75 super sport

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Re: No 12v power to ignition.
« Reply #8 on: February 28, 2012, 11:54:26 AM »
powellml67@yahoo.com thanks again!
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Offline ChuckG750f1

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Re: No 12v power to ignition.
« Reply #9 on: February 28, 2012, 12:02:51 PM »
Sent.
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Life is hard; it's harder if you're stupid.
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1995 HD Softail Custom

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: No 12v power to ignition.
« Reply #10 on: February 28, 2012, 04:26:34 PM »
Quote from: 75 super sport on February 28, 2012, 10:47:49 AM
I am not familiar with kickstand kill switch? Where is this located?

It's located on other bikes, not our's.

Extra green wire with a shielded female connector is a spare. I don't think anyone has determined it's future purported use so just ignore it.
« Last Edit: February 28, 2012, 04:29:12 PM by Jerry Rxman Griffin »
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Online Stev-o

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Re: No 12v power to ignition.
« Reply #11 on: February 28, 2012, 06:29:05 PM »
There was a thread on that, the extra green wire was the ground for your CB radio!
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Offline 75 super sport

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Re: No 12v power to ignition.
« Reply #12 on: February 28, 2012, 08:34:20 PM »
Thanks alot guys. I unplugged the green wire and gave it a minute. Took the fuse out and put it back in and eureka! I have power. My low beam head light and horn dont work, Any suggestions?
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Re: No 12v power to ignition.
« Reply #13 on: February 28, 2012, 08:46:46 PM »
Easiest way to check your horn, run two wires directly to the horn from the battery,
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Offline magconpres

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Re: No 12v power to ignition.
« Reply #14 on: February 28, 2012, 08:47:06 PM »
Possibly a bad switch.
could be the wiring as well.
Low beam should be the white wire from the switch.  The dark blue is the high beam.   You can check them for power in the connections under the tank0.
The horn is grounded by the switch.  Check for power on the black wire at the horn.  If you have power, you can test the horn by grounding the green wire to the frame.  If it goes BEEP, then it's good and the problem is the switch.
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1975 CB400F, ran when I parked it. Cafe Racer bound
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Offline Spanner 1

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Re: No 12v power to ignition.
« Reply #15 on: February 28, 2012, 09:55:43 PM »
Need to get down-and-dirty with every electrical connection on your bike , Start at the battery. Don't stop until all the connectors are completly shiny and tight fitting in their connector mates. Do the big white 6 way alternator plug and the big rectifier plug. Make the male 'spades' bright and a tight fit in their opposites.
Shine the fuse clips and be sure they get a firm grip on each end of the fuse. Look on the back of the fuse block for any burning/melting. These things will stop your bike from running when you are far from home, much more prevalent than some mechanical failure.
You will cure any and all your electrical problems now and in the future ( on the road ) if you do this now.
I know your dying to get your bike running ASAP, but fix the wiring once now and strike it off the list  ;)
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Offline ChuckG750f1

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Re: No 12v power to ignition.
« Reply #16 on: February 29, 2012, 05:48:54 AM »
I think when you finally open the left handlebar control housing you are going to find shorted connections.  It's an easy place to start and it is implicated in every symptom you've had!  I won't mention it again.
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1976 CB750 f1
1995 HD Softail Custom

Offline Xnavylfr

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Re: No 12v power to ignition.
« Reply #17 on: February 29, 2012, 06:21:40 AM »
Try this diagram, all the 750s were very similar  in the wiring. This diagram also shows you the color of the wires as they should be.


http://www.hondachopper.com/garage/cb750k1_wiring_diagram/cb750k1_wiring_diagram.html

http://www.satanicmechanic.org/wiringcodes.shtml

Xnavylfr(CHUCK)
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Offline ChuckG750f1

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Re: No 12v power to ignition.
« Reply #18 on: February 29, 2012, 08:35:41 AM »
I sent him the correct CB750 f1 color diagram yesterday.  I've used it alot for my bike and have not found anything wrong with it yet.
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Life is hard; it's harder if you're stupid.
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1976 CB750 f1
1995 HD Softail Custom

Offline 75 super sport

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Re: No 12v power to ignition.
« Reply #19 on: February 29, 2012, 09:44:32 AM »
Chuck the wiring diagram helped out a lot! Thank you and everyone else for the help. This forum is great!
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